Catheter Assembly Including ECG Sensor And Magnetic Assemblies

ABSTRACT

A stylet for use in guiding a distal tip of a catheter to a predetermined location within the body of a patient. In one embodiment the stylet is configured for use within a lumen of the catheter and comprises a core wire, an ECG sensor, and a magnetic assembly. The ECG sensor senses an ECG signal of a patient when the stylet is disposed within the lumen of the catheter and the catheter is disposed within the body of the patient. The magnetic assembly includes at least one element capable of producing a magnetic or electromagnetic field for detection by a sensor external to the patient. In another embodiment, the stylet includes a pre-shaped distal segment that is deflected with respect to a more proximal portion of the stylet, which in turn causes a distal segment of the catheter to be deflected when the stylet is received within the lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.12/545,762, filed Aug. 21, 2009, now U.S. Pat. No. 9,901,714, whichclaims the benefit of U.S. Provisional Patent Application No.61/091,233, filed Aug. 22, 2008, and titled “Catheter IncludingPreloaded Steerable Stylet;” and U.S. Provisional Patent Application No.61/095,451, filed Sep. 9, 2008, and titled “Catheter Assembly IncludingECG and Magnetic-Based Sensor Stylet,” each of which is incorporatedherein by reference in its entirety.

BRIEF SUMMARY

Briefly summarized, embodiments of the present invention are directed toa stylet for use in guiding a distal tip of a catheter to apredetermined location within the body of a patient. In one embodimentthe stylet is configured for use within a lumen of the catheter andcomprises a core wire, an ECG sensor, and a magnetic assembly. The ECGsensor senses an ECG signal of a patient when the stylet is disposedwithin the lumen of the catheter and the catheter is disposed within thebody of the patient. The magnetic assembly includes at least one elementcapable of producing a magnetic or electromagnetic field for detectionby a sensor external to the patient.

In another embodiment, the stylet includes a pre-shaped distal segmentthat is deflected with respect to a more proximal portion of the stylet,which in turn causes a distal segment of the catheter to be deflectedwhen the stylet is received within the catheter lumen.

These and other features of embodiments of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of embodiments of theinvention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of embodiments of the invention will berendered by reference to specific embodiments thereof that areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The embodimentswill be described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a top view of a catheter assembly including a shaped,torqueable stylet according to one example embodiment of the presentinvention;

FIG. 2 is a top view of the stylet of FIG. 1;

FIG. 3A is a top view of a shaped distal portion of the stylet of FIG.2, according to one possible configuration;

FIG. 3B is a top view of the shaped distal portion of the stylet of FIG.2, according to another possible configuration;

FIG. 3C is a top view of the shaped distal portion of the stylet of FIG.2, according to yet another possible configuration;

FIG. 3D is a top view of the shaped distal portion of the stylet of FIG.2, according to still another possible configuration;

FIG. 4A is a top view of a catheter assembly including a stylet loadedtherein and configured in accordance with one embodiment of the presentinvention;

FIG. 4B is a top view of the stylet of FIG. 4A, according to oneembodiment;

FIG. 5 is a cross sectional view of a distal segment of the stylet ofFIG. 4B, according to one embodiment;

FIGS. 6A-6F are various views of a stylet in accordance with anotherembodiment;

FIG. 7 is a cross sectional view of a distal segment of the stylet ofFIG. 4B, according to another embodiment;

FIG. 8 is a partial cross sectional view of a distal segment of a styletconfigured in accordance with one example embodiment;

FIG. 9 is a partial cross sectional view of a distal segment of a styletconfigured in accordance with another embodiment;

FIG. 10 is a partial cross sectional view of a distal segment of astylet configured in accordance with yet another embodiment;

FIG. 11 is a partial cross sectional view of a distal segment of astylet and catheter configured in accordance with one embodiment;

FIG. 12 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 13 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 14 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 15 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 16 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 17 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 18 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 19 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 20 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment;

FIG. 21 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment; and

FIG. 22 is a cross sectional view of a distal segment of a styletconfigured in accordance with one embodiment.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made to figures wherein like structures will beprovided with like reference designations. It is understood that thedrawings are diagrammatic and schematic representations of exemplaryembodiments of the invention, and are not limiting of the presentdisclosure nor are they necessarily drawn to scale.

FIGS. 1-22 depict various features of embodiments of the presentinvention, which is generally directed, in one embodiment, to a catheterassembly including a pre-loaded stylet therein. In one embodiment, thecatheter assembly includes a distal portion shaped in a bentconfiguration. The bent configuration of the catheter distal portion iscaused by the pre-loaded stylet, which includes a pre-shaped distalsegment deflected in a bent configuration. Thus, the pre-shaped distalsegment of the stylet urges the distal portion of the catheter into asimilar bent configuration.

Further, the pre-loaded stylet is configured to be torqueable, thusenabling the stylet to be rotatable within the catheter lumen. Ahydrophilic coating applied to an outer surface of the styletfacilitates such stylet rotation. Rotation of the shaped stylet enablesthe pre-shaped distal segment to be changed in orientation. This in turncauses a change in orientation of the distal portion of the catheter tooccur. Such “steerability” enables the catheter to be more easily guidedthrough the vasculature of a patient during placement of the catheter.

In another embodiment, a stylet for use in guiding a distal tip of acatheter in which the stylet is disposed to a predetermined locationwithin the vasculature of a patient is disclosed. The stylet includes amagnetic assembly proximate its distal tip for use with an externalmagnetic sensor to provide information relating to generalpositioning/orientation of the catheter tip during navigation throughthe patient vasculature. The stylet further includes an ECG sensorproximate its distal tip for use with an external ECG monitoring systemto determine proximity of the catheter distal tip relative to anelectrical impulse-emitting node of the patient's heart, such as the SAnode in one example. Such electrical impulses are also referred toherein as “ECG signals.” Inclusion of the magnetic and ECG sensors withthe stylet enables the catheter to be guided with a relatively highlevel of precision to a predetermined location proximate the patient'sheart.

For clarity it is to be understood that the word “proximal” refers to adirection relatively closer to a clinician using the device to bedescribed herein, while the word “distal” refers to a directionrelatively further from the clinician. For example, the end of acatheter placed within the body of a patient is considered a distal endof the catheter, while the catheter end remaining outside the body is aproximal end of the catheter. Further, the words “including,” “has,” and“having,” as used herein, including the claims, shall have the samemeaning as the word “comprising.”

Reference is first made to FIG. 1, which depicts a catheter assembly,generally designated at 10 and configured in accordance with one exampleembodiment of the present invention. As shown, the catheter assembly 10includes a catheter 12 having a proximal end 12A, a distal end 12B, anddefining at least one lumen 14 extending therebetween. In the presentembodiment, the catheter is a PICC, though in other embodiments othertypes of catheters, having a variety of size, lumen, and prescribed useconfigurations can benefit from the principles described herein.Further, though shown here with an open distal end, the catheter inother embodiments can have a closed distal end. As such, the presentdiscussion is presented by way of example and should therefore not beconstrued as being limiting of the present invention in any way. Notethat the catheter 12 can be formed from one or more of a variety ofmaterials, including polyurethane, polyvinyl chloride, and/or silicone.

A bifurcation, or hub 16, can be included at the catheter proximal end12A. The hub 16 permits fluid communication between extension tubing 18and 20 and the lumen(s) 14 of the catheter 12. Each extension tubingcomponent 18 and 20 includes on a proximal end a connector 22 forenabling the catheter assembly 10 to be operably connected to one ormore of a variety of medical devices, including syringes, pumps,infusion sets, etc. Again note that the particular design andconfiguration of the afore-described components are exemplary only.

The catheter 12 includes a distal portion 24 as part of the catheterthat is configured for insertion within the vasculature of a patient. Asseen in FIG. 1, the distal portion 24 of the catheter 12 includes adeflected, bent configuration with respect to the more proximal portionof the catheter 12. As will be described further below, this bentconfiguration is caused by a stylet disposed within the catheter andfacilitates relatively easier navigation and placement of the distal tipof the catheter in a preferred location within the patient vasculature.

Together with FIG. 1, reference is now made to FIG. 2. FIG. 1 furthershows a stylet 30 extending from a proximal end of the extension tubing20 and configured in accordance with one embodiment of the presentinvention. As shown in FIG. 2 removed from the catheter 12, the stylet30 includes an elongate core wire that defines a proximal end 30A and adistal end 30B. The stylet 30 is pre-loaded within the lumen 14 of thecatheter 12 such that the distal end 30B is substantially flush with theopening at the catheter distal end 12B, and such that the proximalportion of the stylet extends from the proximal end of the catheter orone of the extension tubes 18 and 20. Note that, though considered hereas a stylet, in other embodiments a guidewire or other catheter guidingapparatus could include the principles of embodiments of the presentdisclosure described herein.

As mentioned, the body of the stylet 30 is configured as an elongatecore wire and is composed of a memory material such as, in oneembodiment, a nickel and titanium-containing alloy commonly known by theacronym “nitinol.” Nitinol possesses characteristics that serve well inthe present application, including shape memory and torqueabilitycharacteristics, as will be explained. In another embodiment, othersuitable materials such as stainless steel could be used for the styletconstruction. In yet another embodiment, it is appreciated that thedistal segment can be manufactured from a memory material such asnitinol, while the more proximal portion of the stylet core wire ismanufactured with stainless steel or other suitable material.

The stylet 30 further includes a distal segment 32 that is pre-shaped tohave a bent configuration with respect to the more proximal portion ofthe stylet. In particular, the stylet distal segment 32 is bent off-axiswith respect to a substantially linear longitudinal axis 36 of thestylet core wire in the view depicted in FIG. 2. Manufacture of thestylet 30 from a shape memory material such as nitinol enables thestylet to be configured such that the core wire retains the curved orother bent distal segment shape shown in FIG. 2 during use with thecatheter assembly 10. The distal segment 32 is “pre-shaped” in that itis manufactured to possess a bent or offset configuration before itsassembly and retains the configuration after insertion within thecatheter 12.

The bent configuration of the distal segment 32 in the embodimentillustrated in FIG. 2 defines an arc or curve having a radius R. Inother embodiments, however, the distal segment can be bent or offsetfrom the more proximal portion of the stylet in other ways, such as inFIG. 3C, for example, where the distal segment is approximately linearlyoffset to define an angle θ with the longitudinal axis of the proximalportion of the stylet 30. Combinations of linear and curved bendprofiles are also possible. These and other possible bent or offsetconfigurations are therefore contemplated as falling within the claimsof the present invention.

Reference is now made to FIG. 3A, which depicts further details of thestylet 30, according to one embodiment. As shown, the pre-shaped distalsegment 32 includes a distal portion of the core wire having a diameterD2 that is reduced with respect to the diameter D1 of the more proximalportion of the core wire. The stylet core wire transitions from diameterD1 to D2 at a smooth, linear tapered transition region 40, though inother embodiments a stepped taper, convex or concave taper, or no taperneed be present.

A tubing sleeve 42 is slid over the reduced diameter stylet core wirealong the distal segment 32 and is sized to substantially match thediameter D1 of the proximal portion of the stylet core wire, though itcan be sized differently, if desired. The sleeve 42 is adhered to thecore wire near the transition region 40 and at the distal end 30B of thecore wire by an adhesive 46, such as a UV, 2-part epoxy, or othersuitable adhesive. So secured, an air gap 48 is created between an outersurface of the core wire and an inner surface of the sleeve 42. In otherembodiments, the air gap can be enlarged, reduced, or eliminated.

In the present embodiment, the sleeve 42 includes reinforcement 44 tomaintain the sleeve in a bent configuration similar to the bentconfiguration of the stylet distal segment core wire. The reinforcement44 can be a metal coil or braided mesh or substrate that is integratedinto the structure of the sleeve 42 and is capable of bending so as toassume and maintain a bent shape similar to that shown in FIG. 3A.Characteristics of the sleeve 42 that can be adjusted so as to modifyits performance include its wall thickness, melt index, and composition.In the present embodiment, the sleeve 42 is composed of polyimide andthe reinforcement 44 is coiled stainless steel. Of course, othersuitable materials can be employed, either in lieu of or in combinationwith, these constituents. In other embodiments, the reinforcement can beconfigured so as to merely strengthen the sleeve and not maintain itsbent configuration, or the reinforcement can be removed from all or aportion of the sleeve. In the latter case, a sleeve having noreinforcement can nevertheless be formed so as to have a pre-shaped,bent configuration. In any of the above embodiments, however, the sleevecan be configured to assist the distal segment 32 of the stylet corewire in urging the distal portion of the catheter 12 into a similar bentconfiguration, as seen in FIG. 1 and as will be explained in furtherdetail below.

As mentioned, the stylet 30 having a pre-shaped distal segment 32, suchas that described in connection with FIG. 3A, is pre-loaded in oneembodiment into the catheter 12 before insertion such that the distalsegment resides within the lumen 14 at the distal portion 24 of thecatheter, placing the distal tips of both the stylet and the catheter insubstantial alignment with one another. Note that in other embodimentsthe distal tips of the stylet and catheter can be in a non-aligningconfiguration, if desired, and that the catheter can include multiplelumens. So positioned, the distal segment 32 of the stylet 30 imparts anurging force on the distal portion 24 of the catheter 12 such that thecatheter distal portion assumes a bent configuration similar to that ofthe stylet distal segment. As such, it is appreciated that while thestylet 30 is loaded within the catheter 12, the distal portion 24 of thecatheter takes on the bent configuration of the distal segment 32 of thestylet. Once the stylet 30 is removed, the catheter 12 is free to returnto an unbent configuration commensurate with its original shape whenmanufactured.

The stylet 30 in one embodiment further includes on its outer surface ahydrophilic coating 38 to assist in rotating the stylet within the lumen14 of the catheter 12 during use. The wettable coating 38 can beactivated, for instance, by flushing the catheter lumen 14 with salineor other aqueous solution, thereby facilitating rotation of the styletwithin the lumen. In other embodiments, no coating is included on thestylet. In yet other embodiments, the coating can be included on aninner surface of the catheter, or the composition of the catheter andstylet can be chosen such that a net low coefficient of friction existsbetween the two surfaces.

A handle 34 can be provided near the proximal end 30A of the stylet 30so as to enable a user to rotate the stylet within the catheter lumen14. Because the stylet 30 is at least partially composed of nitinol orother suitable material in one embodiment, the stylet is configured tobe torqued by user application of a rotational force thereto via thehandle 34. The handle 34 may take one of many shapes and configurations,including that shown in FIGS. 1 and 2, for example. Torqueability of thestylet 30, together with its hydrophilic coating 38, makes possibleselective rotation of the stylet within the catheter lumen 14, which inturn enables selective rotation and orientation of the bent distalsegment 32. As before mentioned, no coating may be necessary in oneembodiment. In addition, the handle 34 is attached to the stylet corewire so as to correspond with the orientation of the bent distal segment32. Thus one can determine the orientation of the direction of bend ofthe distal segment 32 when the distal segment is disposed within thevasculature of a patient by observing the orientation of the handle 34.The handle 34 in one embodiment may include a visual guide or keythereon to assist the clinician in ascertaining the orientation of thebent distal segment 32.

As mentioned, the stylet distal segment 32, having a pre-shaped bentconfiguration, urges the distal portion 24 of the catheter into asimilar bent configuration when the stylet 30 is received in thecatheter lumen 14 as shown and described. Rotation of the stylet 30within the catheter lumen 14 in the manner described above thereforecauses a corresponding change in the orientation of the bentconfiguration of the catheter distal portion 24, shown for example inphantom in FIG. 1. Thus, the catheter distal portion 24 and itscorresponding distal tip are “steerable” via torqueable rotation of thestylet 30 by a clinician grasping and turning the handle 34. Suchsteerability is desirous to enable the catheter distal tip to benavigated through the tortuous vasculature of a patient during placementof the catheter 12. Note that the distal segment 32 is sufficientlyresilient to prevent trauma or damage to the vasculature duringnavigation therein.

In greater detail, with the handle 34 being oriented in a directioncorresponding to the direction of bend in the stylet distal segment 32,the clinician placing the catheter within the patient vasculature canascertain the orientation of the bent catheter distal portion 24, whichis disposed within the vasculature during placement, by observing theorientation of the handle 34. The handle 34 therefore acts as a key indetermining orientation of the bent configuration of the distal segment34 of the stylet 30/distal portion 24 of the catheter 12. This aspectassists the clinician in placing the catheter 12 in the patientvasculature so as to place the distal tip of the catheter 12 in apredetermined position by advancing the catheter 12 with the pre-loadedstylet 30 therein. Once the catheter 12 has been placed as desired, thestylet 30 can be removed from the catheter lumen 14 and correspondingextension tubing 18/20 and the catheter prepared for use.

Reference is now made to 3B and 3C, which show aspects of other possiblestylet distal segment configurations according to embodiments of thepresent invention. The distal segment 32 shown in FIG. 3B includes areduced diameter core wire as in FIG. 3A, but includes no sleevecovering the distal core wire segment. The distal segment 32 shown inFIG. 3C also includes no sleeve, but includes a core wire segment havinga non-reduced diameter with respect to the proximal core wire portion.Thus, it is seen that various core wire diameters and omissions of thesleeve or other components may be intended while still residing withinthe scope of embodiments of the present invention.

Reference is now made to FIG. 3D, which shows yet another example of astylet distal segment according to one embodiment. In particular, thestylet distal segment 32 of FIG. 3D includes a reduced diameter corewire, sleeve 42 having reinforcement 44, and air gap 48, as earlierdescribed in connection with FIG. 3A. A plurality of magnets 60 isdisposed in a portion of the air gap 48. The magnets 60 are employed inthe distal segment to enable the distal segment 32 of the stylet 30 tobe observable by an exterior tip location system configured to detectthe magnetic field of the magnets as the stylet tip advances, togetherwith the catheter distal tip, through the patient vasculature. In thepresent embodiment, the magnets 60 are ferromagnetic of a solidcylindrical shape, but in other embodiments they may vary from thisdesign in not only shape, but composition, number, size, magnetic type,and position in the stylet distal segment. For instance, the magneticassembly may include a single or multiple electromagnets disposed in thedistal segment in a uni-polar or bi-polar design, in one embodiment.

Note that embodiments of the present disclosure may vary from what isexplicitly described herein. For instance, differences in sleeve, airgap, and core wire grind may be present in a stylet distal segment so asto alter bend and resiliency characteristics thereof while still fallingunder the present claims.

FIGS. 4A-11 depict various features of further embodiments of thepresent disclosure, directed as before to a stylet for use in guiding adistal tip of a catheter in which the stylet is disposed to apredetermined location within the vasculature of a patient. The styletincludes a magnetic assembly proximate its distal tip for use with anexternal magnetic sensor to provide information regarding generalpositioning/orientation of the catheter tip during navigation throughthe patient vasculature. The stylet further includes an ECG sensorproximate its distal tip for use with an external ECG monitoring systemto determine proximity of the catheter distal tip relative to anelectrical impulse-emitting node of the patient's heart, such as the SAnode in one example. Such electrical impulses are also referred toherein as “ECG signals.” Inclusion of the magnetic assembly and ECGsensor with the stylet enables the catheter to be guided with arelatively high level of precision to a predetermined location proximatethe patient's heart.

Reference is first made to FIG. 4A, which depicts a catheter assembly,generally designated at 110 and configured in accordance with oneexample embodiment of the present invention. As shown, the catheterassembly 110 includes a catheter 112 having a proximal end 112A, adistal end 112B, and defining at least one lumen 114 extendingtherebetween. In the present embodiment, the catheter is aperipherally-inserted central catheter (“PICC”), though in otherembodiments other types of catheters, having a variety of size, lumen,and prescribed use configurations can benefit from the principlesdescribed herein. Further, though shown here with an open distal end,the catheter in other embodiments can have a closed distal end. As such,the present discussion is presented by way of example and shouldtherefore not be construed as being limiting of the present invention inany way.

A hub 116 is included at the catheter proximal end 112A. The hub 116permits fluid communication between extension tubing 118 and 120 and thelumen(s) 114 of the catheter 112. Each extension tubing component 118and 120 includes on a proximal end a connector 122 for enabling thecatheter assembly 110 to be operably connected to one or more of avariety of medical devices, including syringes, pumps, infusion sets,etc. Again note that the particular design and configuration of theafore-described components are exemplary only. For instance, in oneembodiment, the catheter need not include a hub or extension legs. Thecomposition of the catheter in this and other embodiments describedherein includes a suitable material, such as polyurethane, silicone,etc.

The catheter 112 includes a distal portion 124 configured for insertionwithin the vasculature of a patient. The catheter 112 is flexible so asto enable it to bend while being advanced through the patientvasculature.

Together with FIG. 4A, reference is now made to FIG. 4B. FIG. 4A furthershows a stylet 130 extending from a proximal end of the extension tubing120 and configured in accordance with one embodiment of the presentinvention. As shown in FIG. 4B, the stylet 130 as removed from thecatheter 112 defines a proximal end 130A and a distal end 130B andgenerally includes a core wire 131, a handle 134, and a tether 135. Thestylet 130 is pre-loaded within the lumen 114 of the catheter 112 in oneembodiment such that the distal end 130B is substantially flush with theopening at the catheter distal end 112B, and such that the proximalportion of the core wire 131, the handle 134, and the tether 135 arelocated proximal to the proximal end of the catheter or one of theextension tubes 118 and 120. Note that, though described herein as astylet, in other embodiments a guidewire or other catheter guidingapparatus could include the principles of the present inventiondescribed herein.

The core wire 131 defines an elongate configuration and is composed of asuitable stylet material including stainless steel or a memory materialsuch as nitinol in one embodiment. Though not shown here, manufacture ofthe core wire 131 from nitinol in one embodiment enables the portion ofthe core wire corresponding to a distal segment 132 of the stylet 130 tohave a pre-shaped bent configuration, as has already been described.

Further, the nitinol construction lends torqueability to the core wire131. Thus, the pre-shaped core wire distal segment 132, together withcore wire torqueability, enables the distal segment of the stylet 130 tobe manipulated while disposed within the catheter lumen 114 duringcatheter insertion, which in turn enables the distal portion 124 of thecatheter 112 to be navigated through the vasculature during catheterinsertion. In the presently illustrated embodiment, no pre-shaping ofthe stylet distal segment is shown.

Note also that the present stylet can be employed in a catheterplacement system that employs one or more of ultrasound, magnetic-basedstylet tip tracking, and ECG-based tip navigation/position confirmationtechnologies to accurately place a catheter in the vasculature of apatient. Details regarding aspects of an example of such a system aregiven below, and can also be found in U.S. Patent ApplicationPublication No. 2009/0156926, entitled “Integrated System forIntravascular Placement of a Catheter,” filed Nov. 25, 2008; and U.S.patent application Ser. No. 12/426,175, entitled “Systems and Methodsfor Breaching a Sterile Field for Intravascular Placement of aCatheter,” filed Apr. 17, 2009, each which is incorporated herein byreference in its entirety.

A handle 134 is provided at a proximal end 131A of the stylet 130 so asto enable insertion/removal of the stylet from the catheter lumen 114.In embodiments where the stylet core wire 131 is torqueable, the handle134 enables the core wire 131 to be rotated within the catheter lumen114, such as when rotation of a pre-shaped distal segment 132 of thestylet 130 is desired to assist in navigating the catheter distalportion 124 through the vasculature of the patient. In this case, thehandle 134 is attached to the stylet core wire so as to correspond withthe orientation of the bent distal segment 132. Thus one can determinethe orientation of the direction of bend of the distal segment 132 whenthe distal segment is disposed within the vasculature of a patient byobserving the orientation of the handle 134. The handle 134 may includea guide or key thereon to assist the clinician in ascertaining theorientation of the bent distal segment 132.

Rotation, insertion, and/or removal of the stylet 130 via the handle 134is further facilitated in one embodiment by application of a hydrophiliccoating 138 to an outer surface of the core wire 131 and accompanyingsleeve to be described further below. The wettable hydrophilic coating138 can be activated, for instance, by flushing the catheter lumen 114with saline or other aqueous solution, thereby facilitating rotation ofthe stylet within the lumen. The handle 134 may take one of many shapesand configurations, including that shown in FIGS. 2, 4A, and 6A, forexample. Note also that in an unbent configuration, the core wire 31 ofthe stylet 130 defines a substantially linear longitudinal axis 136.

In the present embodiment, the handle 134 attaches to a distal end ofthe tether 135. In the present embodiment, the tether 135 is a flexible,shielded cable housing a plurality of electrically conductive wires. Thewires are electrically connected to components, to be discussed below,disposed in the distal segment 132 of the stylet 130, and as such, theyprovide a conductive pathway from the distal segment through to theproximal end 130A of the stylet, where an electrical connector 156 isattached. As will be explained, the electrical connector 156 can takeone of many forms and is configured for operable connection to anexternal magnetic and/or ECG sensor device in assisting navigation ofthe stylet 130 and catheter 112 to a desired location within the patientvasculature. Note that in another embodiment, the stylet can beun-tethered and electrical connectivity with the stylet distal segmentcomponents can be achieved by attaching temporary clips at the handlewhere the electrical wires from such components exit the stylet, forinstance.

Reference is now made to FIG. 5, which depicts further details of thestylet 130, according to one embodiment. As shown, the distal segment132 includes a distal portion of the core wire 131 defining a diameterD2 that is reduced with respect to the diameter D1 of the more proximalportion of the core wire. The stylet core wire transitions from diameterD1 to D2 at a tapered transition region 140, though in other embodimentsno taper need be present. The reduced diameter portion of the core wirelends desired stiffness and tensile properties thereto, though it isappreciated that in other embodiments no reduction in core wire diameteris necessary.

A sleeve 142 is slid over the reduced diameter stylet core wire alongthe distal segment 132 and is sized to substantially match the diameterD1 of the proximal portion of the stylet core wire. The sleeve 142 isadhered to the core wire near the transition region 140 and at thedistal end 130B of the core wire by an adhesive 146, such as a UV,2-part epoxy, or other suitable adhesive. So secured, an air gap 148 iscreated between an outer surface of the core wire and an inner surfaceof the sleeve 142. In other embodiments, the air gap can be enlarged,reduced, or eliminated.

In the present embodiment, the sleeve 142 includes reinforcement 144 toassist the core wire 131 in providing proper stylet distal end stiffnessand, in cases where the distal segment of the stylet is pre-shaped in abent configuration, to assist in maintaining the core wire in the bentconfiguration. The reinforcement 144 can be a metal coil or braided meshor substrate that is integrated into the structure of the sleeve 142 andis capable of manipulation so as to assume and maintain a bent shape, ifdesired.

Characteristics of the sleeve 142 that can be adjusted so as to modifyits performance include its wall thickness, melt index, and composition.In the present embodiment, the sleeve 142 is composed of materialsincluding polyimide and the reinforcement 144 is coiled stainless steel.Of course, other suitable materials can be employed, either in lieu ofor in combination with, these constituents. As mentioned, in embodimentsof the present invention the reinforcement can be configured so as tomerely strengthen the sleeve and not maintain a bent configuration as inFIG. 5, to maintain a bent configuration as in FIG. 6A, or thereinforcement can be removed from all or a portion of the sleeve.

The stylet distal segment 132 further includes an ECG sensor or sensorassembly, generally designated at 150, according to one embodiment. TheECG sensor assembly 150 enables the stylet, preloaded in the lumen 114of the catheter 112 during patient insertion, to be employed indetecting an intra-atrial ECG signal produced by an SA or other node ofthe patient's heart, thus assisting in navigating the distal end 112B ofthe catheter to a predetermined location within the vasculatureproximate the patient's heart. Thus, the ECG sensor assembly 150 servesas an aide in confirming proper placement of the catheter distal end112B.

In the embodiment illustrated in FIG. 5, the ECG sensor assembly 150includes a distal portion of the core wire 131, which is electricallyconductive, as is the rest of the core wire. A conductive distal coil152 is disposed about the distal portion of the core wire 131 adjacentthe core wire distal tip 131B. The distal coil 152 is composed of aconductive material, such as stainless steel. A tip weld 154 is includedon the core wire distal tip 131B to bond the distal coil 152 to the corewire distal tip 131B. The tip weld 154 further provides an atraumaticdistal tip configuration for the core wire 131. In another embodiment,the distal coil 152 is configured so as to define a diameter equal tothat of the tubing sleeve 142 and to define a constant diameter alongthe stylet length. In yet another embodiment, no coil is included.

Before catheter placement, the stylet 130 is preloaded into the lumen114 of the catheter 112. Note that in one embodiment the stylet 130 ispreloaded within the catheter lumen 114 before use such that the distalsegment 132 of the stylet resides within the lumen at the distal portion124 of the catheter, placing the distal tips of both the stylet and thecatheter in substantial alignment with one another. Once the catheterhas been introduced into the patient vasculature and is advanced towardthe patient's heart, the distal portion of the core wire 131, beingelectrically conductive, begins to detect the electrical impulsesproduced by the SA node or other suitable node of the patient's heart.The distal coil 152 is included about the core wire distal tip 131B toincrease the relative surface area of the core wire distal portion so asto improve reception of the electrical impulses from the SA node. Notethat other structures could be provided to provide the samefunctionality. As such, the ECG sensor assembly 150 serves as a sensoror electrode for detecting the ECG heart signals. The elongate core wire131 proximal to the core wire distal segment serves as a conductivepathway to convey the electrical impulses produced by the SA node andreceived by the ECG sensor assembly 150 away from the distal segment 132of the stylet 130 to the tether 135.

An electrical wire or other suitable structure in the tether 135 conveysthe signals to an ECG sensor module located external to the patient. Thetether 135 is operably connected to the ECG sensor module via theelectrical connector 156, or other suitable direct or indirectconnective configuration. Monitoring of the ECG signal received by theexternal sensor module enables a clinician to observe and analyzechanges in the signal as the catheter advances toward the SA node. Whenthe received ECG signal matches a desired profile, the clinician candetermine that the catheter distal end 112B has reached a desiredposition with respect to the SA node. In one implementation, forexample, this desired position lies within the lower one-third (⅓^(rd))portion of the superior vena cava (“SVC”). Once it has been positionedas desired, the catheter 112 may be secured in place and the stylet 130removed from the catheter lumen 114.

In the present embodiment of FIG. 5, the distal segment 132 of thestylet 130 further includes a magnetic assembly, generally designated at160. The magnetic assembly 160 in the illustrated embodiment includes aplurality of magnets 162 disposed in a portion of the air gap 148, andas such the magnets are interposed between an outer surface of the corewire 131 and an inner surface of the sleeve 142. In the presentembodiment, the magnets 162 are ferromagnetic of a solid cylindricalshape stacked end-to-end, but in other embodiments they may vary fromthis design in not only shape, but also composition, number, size,magnetic type, and position in the stylet distal segment. In oneparticular embodiment, the magnets 162 include neodymium. In otherembodiments, other rare-earth or alternative types of magnets ormagnetic elements may be employed. In yet other embodiments, anelectromagnet or other element capable of producing an electromagneticfield that can be externally detected and monitored may also be used.

The magnets 162 are employed in the stylet distal segment 132, preloadedwithin the lumen 114 of the catheter 112 during catheter placementwithin the patient's vasculature, to enable the position of the distalsegment to be observable relative to a magnetic sensor placed in closeproximity to the patient's body as part of an exterior tip locationsystem. The tip location system is configured to detect the magneticfield of the magnets 162 as the stylet distal segment 132 advances,together with the catheter distal portion 124, through the patientvasculature. In this way, a clinician placing the catheter 112 is ableto generally determine the location, orientation, and/or advancement ofthe catheter distal end 112B within the patient vasculature and detectwhen catheter malposition is occurring, such as advancement of thecatheter along an undesired vein, for instance.

The ECG sensor assembly 150 and magnetic assembly 160 can work inconcert in assisting a clinician in placing a catheter within thevasculature. Generally, the magnetic assembly 160 of the stylet 130assists the clinician in generally navigating the vasculature frominitial catheter insertion into the vasculature so as to place thedistal end 112B of the catheter 112 in the general region of thepatient's heart. The ECG sensor assembly 150 can then be employed toguide the catheter distal end 112B to the desired location within theSVC by enabling the clinician to observe changes in the ECG signalsproduced by the heart as the stylet distal segment and its ECG sensorassembly approach the SA node. Again, once a suitable ECG signal profileis observed, the clinician can determine that the distal end of both thestylet 130 and catheter 112 have arrived at the desired location withrespect to the patient's heart.

FIGS. 6A-6F depict the stylet 130 for use in a catheter, such as thecatheter 110, according to one embodiment. As shown, the stylet 130includes the core wire 131 attached to the handle 134, with the tether135 extending proximally from the handle to the electrical connector 156to enable interconnection with an external ECG sensor module or othersuitable device for receiving ECG signals detected by the ECG sensorassembly of the stylet. Though not shown here, in one embodiment thestylet 130 can include a shaped distal portion as described inconnection with FIGS. 1-3D above, such that a distal portion of thecatheter is deflected when the stylet is preloaded therein. Note,however, that the discussion to follow applies to stylets including bothshaped and non-shaped distal segments.

The stylet 130 shown in FIG. 6B includes the core wire 131 and thedistal segment 132. As shown in FIGS. 6C and 6D, the core wire 131reduces from a diameter D1 to a diameter D2 over a relatively longertransition region 140 than in the previous embodiment. The portion ofthe core wire 131 corresponding to the transition region 140 is disposedwithin the sleeve 142, which attaches to the core wire by the adhesive146 in the manner shown in FIG. 6C. The air gap 148 is defined betweenthe core wire 131 and the sleeve 142, as before. The reduced diameterportion of the core wire 131 is deflected from an axially centralposition in the sleeve to an offset position so as to extend adjacent toa portion of the inner surface of the sleeve 142, as shown in FIG. 6D.The core wire 131, in this deflected state, extends to its distal tip131B, which corresponds to the distal end 130B of the stylet 130.

The deflected position of the core wire 131 provides space for theplacement of a plurality of magnetic elements, in this case permanentmagnets 162, along a portion of the length of the distal segment 132. Asillustrated in FIGS. 6B, 6D, and 6E, 20 cylindrical permanentferromagnetic magnets are placed end to end. Of course, the type,number, shape, and arrangement of the magnets or other magnetic elementscould vary from what is depicted and described herein. So configured,the magnets 162 define the magnetic assembly 160 that enables the distalend 130B of the stylet 130 to be located via an external magnetic sensormodule during a procedure to place the catheter in the patientvasculature. For example, in one embodiment, the magnets 162 areemployed in the stylet distal segment 132 to enable theposition/orientation of the stylet distal end 130B to be observablerelative to an external sensor placed on the patient's chest. As hasbeen mentioned, the external sensor is configured to detect the magneticfield of the magnets 162 as the stylet advances with the catheterthrough the patient vasculature. In this way, a clinician placing thecatheter is able to generally determine the location/orientation of thecatheter distal end within the patient vasculature and detect whencatheter malposition is occurring, such as advancement of the catheteralong an undesired vein, for instance.

An electrically conductive epoxy 166 fills the hollow distal end of thesleeve proximate the stylet distal end 130B. The epoxy 166 is inelectrical communication with the core wire 131 and serves to increasethe relative surface area of the core wire 131 at the distal tip 131Bthereof. So configured, the distal portion of the core wire 131 andconductive epoxy 166 define an ECG sensor, with the rest of the corewire defining a conductive pathway with respect to the sensor, thusenabling the location of the stylet distal end 130B and correspondingcatheter distal end 112B to be positioned near the SA node of thepatient's heart using an external ECG sensor module, in the manner asdescribed above. Thus, the magnetic assembly and ECG sensor assemblyboth provide assistance in navigating a catheter or other indwellingdevice: the magnetic assembly by providing position/orientation data forthe catheter, and the ECG sensor assembly providing proximity data forthe catheter with reference to an ECG-signal emitting component, such asthe SA node of the patient's heart. These modalities can be usedexclusively of one another, successively, or in concert to aid incatheter advancement. Note that in one embodiment the conductive epoxy166 can be rounded to provide a rounded stylet distal end 130B. Inanother embodiment, the conductive epoxy can be replaced by anotherconductive material such as stainless steel or other suitable metal,etc.

As a brief example of the use of the stylet magnetic and ECG sensorassemblies in assisting in the placement of a catheter, in oneembodiment an external sensor is employed by a catheter placement systemto detect a magnetic field produced by the magnetic elements of thestylet, which is removably predisposed within the lumen of the catheterduring catheter insertion and advancement. The external sensor can beplaced on the chest of the patient during catheter insertion to enablethe magnetic field of the stylet magnetic elements, disposed in thecatheter as described above, to be detected during catheter transitthrough the patient vasculature. As the magnetic elements of the styletmagnetic assembly are co-terminal with the distal end of the catheter,detection by the external sensor of the magnetic field of the magneticelements provides information to the clinician and enables the clinicianto monitor the position/orientation of the catheter distal end duringits transit. Such information can be displayed on a display unit of thecatheter placement system for instance. In this way, a clinician placingthe catheter is able to generally determine the location/orientation ofthe catheter distal end within the patient vasculature relative to theTLS sensor 50 and detect when catheter malposition, such as advancementof the catheter along an undesired vein, is occurring.

As described, the stylet further includes an ECG sensor as a sensingcomponent for sensing ECG signals produced by the SA node. In oneembodiment the ECG sensor of the stylet works in concert with referenceand ground ECG electrodes placed on the skin surface of the patient. ECGsignals detected by the stylet ECG sensor can be received by theexternal sensor referred to above or other suitable component of acatheter placement system, together with signals received by thereference and ground electrodes on the patient's skin. These data can beprocessed and monitored as the stylet-equipped catheter advances throughthe patient vasculature. In one embodiment, an electrocardiogramwaveform is reproduced on the display using the ECG data. The clinicianplacing the catheter can monitor the ECG data to determine optimumplacement of the distal tip of the catheter, such as proximate the SAnode in one embodiment. In one implementation, monitoring of themagnetic assembly data are employed during initial advancement of thecatheter through the patient vasculature, while the ECG sensor assemblydata are monitored as the catheter approaches a desired final locationnear the heart, though other combinations of these modalities are alsocontemplated, including simultaneous use of both modalities in oneembodiment.

Note that, in contrast to what is shown in FIGS. 6B-6E, the distalsegment of the stylet can be configured such that it defines a constantoutside diameter with respect to the more proximal portion thereof.

As has been previously mentioned, other types of magnetic elements,alternative to the permanent magnets described in connection with FIGS.5 and 6A-6E, may be included with the stylet 130 to form a portion ofthe magnetic assembly 160 for enabling the position/orientation of thecatheter distal end 112B to be generally determined during vasculaturenavigation. FIG. 7 depicts an example of one such alternative, whereinan electromagnetic (“EM”) coil 172 is employed in the magnetic assembly160 of the stylet distal segment 132. The EM coil 172 is depicted in thepresent embodiment as a winding of conductive wire, such as insulatedcopper wire, wound about a portion of the distal core wire 131 in theair gap 148 within the sleeve 142. Note that the covering of the EM coil172 by the sleeve 142 provides a secondary level of electrical isolationof electrical energy for the EM coil 172. The coil wire is electricallyinsulated in the present embodiment so as to prevent its interferingwith the ECG signals carried by the core wire 131. Lead wires 174operably connect with the EM coil 172 and extend proximally along thecore wire 131, through the handle 134 and tether 135 to terminate at theconnector 156. The lead wires 174 are disposed along the core wire 131and the rest of the stylet 130 in a free floating, strain reliefconfiguration in the present embodiment so as to prevent detachmentthereof from the EM coil 172. A suitable power source can be operablycoupled to the lead wires 174 to provide electricity to the EM coil 172.

When energized, the EM coil 172 produces an electromagnetic field thatis detectable by an external sensor module in a manner similar to thatdescribed in connection with FIG. 5. Note that the relative strength ofthe field produced by the EM coil 172 is dependent on various factorsincluding the length of the wire from which the coils are made, numberof coil windings, and the thickness of the core wire 131 over which thecoil is wound. As such, it is appreciated that the electromagnetic fieldof the EM coil 172 can be varied by altering these and other aspects ofthe magnetic assembly 160.

A stylet configured in accordance with yet another embodiment is shownin FIG. 8. The stylet 130 of FIG. 8 includes the ECG sensor assembly 150and magnetic assembly 160, as before. In contrast to the previousembodiment, the EM coil 172 is not disposed within the sleeve 142.Rather, a distal end of the sleeve 142 terminates at and abuts aproximal end of the EM coil 172. The lead wires 174 for the EM coil 172are fed through the hollow interior of the sleeve 142 to the handle andtether.

The ECG sensor assembly 150 is disposed proximally of the magneticassembly 160 and has a configuration differing from previousembodiments. As shown, the ECG sensor assembly 150 here includes two ECGleads 182. Each ECG lead 182, defining an annular band is disposed abouta portion of an outer surface of the sleeve 142 is operably connected toa respective ECG lead wire 174. Each of the ECG lead wires 174 extendsthrough the hollow interior of the sleeve 142 to the handle and tether,terminating at the electrical connector 156 or other suitabletermination. As has been explained, the ECG leads 182 operably connectwith an external ECG sensor module, via the lead wires 174 and connector156, to enable the catheter distal end 112B to be navigated through apatient's vasculature to a predetermined location proximate the heart ofthe patient. The stylet 130 further includes an atraumatic tip 188 ofepoxy, UV adhesive, or other suitable material.

Note that the annular band structure of the ECG leads of FIG. 8 aremerely one example of leads that can be included with thestylet/catheter assembly to enable ECG signals produced by the heart tobe detected and forwarded to an external ECG sensor module. As such, thedepictions and accompanying descriptions herein should not be consideredlimiting of embodiments of the present invention in any way. Note alsothat the number and position of the ECG leads on the stylet or cathetercan vary from what is shown and described herein.

FIGS. 9-11 depict additional possible embodiments of the stylet 130 andcatheter assembly 110. In FIG. 9, the stylet distal segment 132 includesthe magnetic assembly 160 and ECG sensor assembly 150 as in FIG. 8. Incontrast to FIG. 8, however, the ECG lead wires 184 are encapsulatedwithin the wall of the sleeve 142 to provide strain relief for the leadwires and to facilitate ease of manufacturability. Such a configurationalso frees up relatively more space in the central portion of thestylet. FIG. 10 shows an embodiment similar to that of FIG. 9, with thesleeve 142 being extended over the EM coil 172 so as to substantiallycover the entirety of the stylet distal segment 132.

In FIG. 11, the stylet 130 is shown disposed in the lumen 114 of thecatheter 112 and including the sleeve 142 and magnetic assembly 160 in aconfiguration similar to that shown in FIG. 8. In the presentembodiment, however, the ECG sensor assembly 150 is not included on thestylet 130, but rather includes the ECG leads 182 disposed on thecatheter itself. Particularly, the ECG leads 182 are integrated into thewall of the catheter such that an outer surface of each lead is exposedat the outer surface of the catheter. This configuration enables the ECGleads 182 of the ECG sensor assembly 150 to serve as electrodes in themanner previously described, but on a catheter having a closed distalend as shown in FIG. 11. The ECG lead wires 184 are electricallyconnected to the ECG leads 182 and disposed within the wall of thecatheter itself so as to extend proximally to an external ECG sensormodule or other suitable device.

Thus, placement of the ECG leads 182 at an outer catheter surface asshown in FIG. 11 enables the leads to act as electrodes and be incontinual contact with the blood present in the vasculature of thepatient, which blood serves as a conducting medium for the ECG signalfrom the heart. Note that in previous embodiments, the ECG leadsdisposed on the stylet itself are in contact with the blood most oftenvia a catheter having an open proximal end. Again, it should be notedthat the embodiments depicted in FIGS. 8-11 are exemplary of the variouspossible configurations for the stylet and its magnetic and ECG sensorassemblies, and that the type, size, and number of elements of thesecomponents may be varied as one skilled in the art will appreciate. Forinstance, the ECG sensor can be included on a stylet without themagnetic assembly present in one embodiment.

Attention is now directed generally to FIGS. 12-22, which depict furtherexamples of the distal segment 132 of the stylet 130 including bothmagnetic and sensor assemblies, according to present embodiments. InFIG. 12, the distal segment 132 includes the tubing 142 inside which isdisposed a distal portion of the core wire 131, terminating at the corewire distal end 131B. The magnetic assembly 160, including a pluralityof permanent magnets 162 or other suitable magnetic/electromagneticelements, is disposed distally to the core wire 131, though otherpositional configurations for the magnetic assembly are possible. Aconductive wire 190 proximally extends within the tubing 142 from thestylet distal end 130B to the proximal end of the stylet for connectionwith a suitable ECG sensor module or other suitable monitoring device. Adistal end 190B of the conductive wire 190 is substantially co-terminalwith the stylet distal end 130B, though other more proximal terminatingconfigurations are also possible. A conductive epoxy 166 is included atthe distal end of the tubing 142 to secure the conductive wire distalend 190B and increase the conductive surface area for ECG signalmonitoring by the ECG sensor, implemented here as the distal portion ofthe conductive wire 190. Of course, other suitable tip configurationscan be used, including atraumatic tips, tip welds, non-conductiveadhesives, or nothing at all. In another embodiment, the conductive wirecan be embedded within the tubing and is exposed only at the distal endof the stylet.

The embodiment of FIG. 13 is similar to that of FIG. 12, wherein theconductive wire 190 does not extend the length of the stylet 130 butrather is connected at a proximal end 190A thereof to the core wire 131.Thus the conductive pathway from the conductive wire distal end 190B,which serves as the ECG sensor, is established by the lengths of boththe conductive wire 190 and the core wire 131. The conductive wireproximal end 190A can be secured to the core wire via a weld, adhesive,etc. This embodiment may be used, for example, where the tubing 142 doesnot proximally extend the entire length of the stylet 130, but ratheronly along the distal segment thereof. Indeed, in the embodimentsdescribed herein, the tubing can extend along all or only a portion ofthe stylet length.

In FIG. 14, a conductive coil 194 proximally extends within the tubing142 and about the magnetic assembly 160 from the stylet distal end 130Bto a connection point with the core wire 131 at the proximal end 194A ofthe coil. The conductive coil proximal end 194A can be secured to thecore wire 131 via a weld, adhesive, etc. A distal end 194B of theconductive coil 194 is substantially co-terminal with the stylet distalend 130B, though other more proximal terminating configurations are alsopossible. A conductive epoxy 166 is included at the distal end of thetubing 142 to secure the conductive coil distal end 194B and increasethe conductive surface area for ECG signal monitoring by the ECG sensor,implemented here as the distal portion of the conductive coil 194. Inother embodiments, the conductive epoxy or other suitable material canextend a greater or lesser distance into the tubing 142 than what isshown in the accompanying drawings. In another embodiment, theconductive coil can proximally extend the length of the stylet 130 forconnection with a suitable ECG sensor module or other suitablemonitoring device. In yet another embodiment, a distal portion of thecore wire can be shaped, such as via grinding, then coiled to form aconductive coil that is integral to the core wire.

In FIG. 15, the tubing 142 can be made electrically conductive, such asvia impregnation therein of a conductive material, or by coating aninner or outer surface thereof with a conductive material. Thus a distalportion of the tubing 142 at the distal end 130B of the stylet 130serves as an ECG sensor and more proximal portions of the tubing definea conductive pathway for carrying the ECG signals therefrom.

In FIG. 16, internal tubing 198 can be included within the tubing 142 ofthe stylet distal segment 132 as part of an ECG sensor assembly. In thepresent embodiment, a proximal end 198A of the internal tubing 198 isattached to a portion of the core wire 131 via heat-shrinking, adhesive,etc., while a distal end 198B is substantially co-terminal with thestylet distal end 130B or is in intimate contact with the conductiveepoxy 166 so as to enable the reception of ECG signals for transmissionalong the internal tubing 198 and core wire 131 to a suitable ECG sensormodule external to the patient, as has been described.

In FIG. 17, the tubing 142 from earlier embodiments is replaced with aconductive tubing structure, such as a metallic hypotube 202, whichattaches to the core wire 131 at a proximal end 202A and extends to thestylet distal end 130B of the stylet 130 where its distal end 202Bcontacts the conductive epoxy 166. The hypotube 202 can includeperforations 204, such as horizontal, vertical, round, or helicalnotches or through-holes completely or partially defined through thehypotube surface so as to increase flexibility of the hypotube.

Note that, in this and other embodiments, the conductive epoxy 166 orother tip configuration, such as atraumatic tips, adhesives, tip welds,etc., can be suitable shaped as seen in FIG. 17 so as to easeadvancement of the catheter and stylet through patient vasculature. Inone embodiment for example, the conductive epoxy tip can be replaced bya tip including stainless steel, either pre-formed before attachment,e.g., via welding, adhesive, etc., to the stylet distal end or shapedafter attachment. Such a tip can be attached directly to the stylet corewire, to another conductive wire in the stylet, or to another ECG sensorconfiguration.

FIG. 18 shows another tubing embodiment, wherein the tubing is definedby a conductive external coil 208, attached at a proximal end 208Athereof and extending to a distal end 208B, which is in contact with theconductive epoxy 166 at the stylet distal end 130B. A safety wire 210can be included so as to extend between a distal portion of the corewire 131 and the distal tip epoxy 166 so as to prevent separation of theexternal coil 208 from the stylet 130. In another embodiment, the safetywire can be replaced with internal tubing that is disposed about themagnetic assembly 160.

In FIG. 19, the conductive epoxy 166 extends proximally from the distalend 130B of the stylet 130, contained by the tubing 142, so as to be inelectrical communication with the core wire 131. Thus, a distal portionof the conductive epoxy 166 serves as an ECG sensor, while more proximalportions thereof provide a conductive pathway, together with the corewire, to enable the transmission of ECG signals through the stylet 130.Note that in another embodiment, the tubing can extend the length of thestylet.

In FIG. 20, an annular conductive ring 214 is included as an ECG sensorat the stylet distal end 130B and is connected to a lead wire 216 thatextends proximally along the length of the stylet 130 for connectionwith a suitable ECG sensor module or other suitable device. The ring 214can be inset into the tubing 142 and can be in electrical communicationwith the conductive epoxy 166. As before, the conductive epoxy can beomitted from the design. In another embodiment, the lead wire 216 can beelectrically connected to the core wire instead of extending the entirelength of the stylet.

In FIG. 21, a conductive coil 218 is positioned distal to and attachedto the tubing 142. A tip weld 154 is formed on the stylet distal end130B so as to electrically connect with the conductive coil 218. Theconductive wire 190 extends distally from the core wire 131 to the tipweld 154 as shown in FIG. 21, or to the conductive coil 218. In anotherembodiment, the conductive wire can extend the length of the stylet. Inyet another embodiment, the conductive coil can be replaced by aconductive hypotube, if desired, which can act as filler material forthe plasma weld that forms the tip weld 154.

In FIG. 22, the core wire 130 includes a distal tip 131B that defines anatraumatic tip configuration, with the conductive epoxy 166 included tosecure the distal tip to the tubing 142. Such a core wire distal tip canbe formed by grinding, plasma welding, etc., and provides an ECG sensorwith relatively large surface area for reception of ECG signals.

It is noted that in example embodiments, distal tips can be formed by avariety of procedures, including grinding or plasma welding as discussedin connection with FIG. 22, insertion and adhesion to the stylet of analready formed tip, insertion of a conductive slug into the stylettubing that is then melted and formed with a die, etc. It should befurther noted that the embodiments shown in the previously describeddrawings are merely examples of possible configurations for providing amagnetic assembly and an ECG sensor with a stylet for guidance of acatheter or other indwelling device within the body of a patient. Assuch, the claims of the present disclosure should not be construed asbeing limited to only those embodiments explicitly described herein.

Embodiments of the present invention may be embodied in other specificforms without departing from its spirit or essential characteristics.The described embodiments are to be considered in all respects only asillustrative, not restrictive. The scope of the present disclosure is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes that come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A catheter assembly, comprising: a styletincluding: a core wire having a straight proximal segment aligned with alongitudinal axis of the core wire, and a pre-shaped distal segmenthaving a bent configuration deflected from the longitudinal axis; and asleeve positioned over the pre-shaped distal segment to maintain thepre-shaped distal segment in the bent configuration; and a catheterhaving a distal portion, the core wire pre-shaped distal segmentdesigned to bend the distal portion into the bent configuration uponinsertion of the stylet into the lumen.
 2. The catheter assemblyaccording to claim 1, wherein the stylet includes a memory shapematerial, and wherein the pre-shaped distal segment of stylet defines anarc shape.
 3. The catheter assembly according to claim 2, wherein thestylet includes nitinol, and wherein the stylet further includes ahandle to axially rotate the stylet.
 4. The catheter assembly accordingto claim 1, wherein the proximal segment of the core wire has a firstdiameter, and wherein the distal segment of the core wire includes asecond diameter less than the first diameter.
 5. The catheter assemblyaccording to claim 4, wherein the core wire transitions from the firstdiameter to the second diameter along a tapered region.
 6. The catheterassembly according to claim 5, wherein a sleeve is adhered to the corewire at a proximal end of the tapered region.
 7. The catheter assemblyaccording to claim 6, wherein the stylet comprises an air gap between anouter surface of the distal segment of the core wire and an innersurface of the sleeve.
 8. The catheter assembly according to claim 7,further comprising a magnetic element disposed in the air gap, themagnetic element having a magnetic field strength sufficient to bedetectable following insertion of the catheter assembly into a patient.9. The catheter assembly according to claim 8, wherein the magneticelement is a plurality of permanent magnets.
 10. The catheter assemblyaccording to claim 8, wherein the magnetic element is one or moreelectromagnets.
 11. The catheter assembly according to claim 1, whereinthe sleeve includes a reinforcement element.
 12. The catheter assemblyaccording to claim 11, wherein the reinforcement element is selectedfrom the group consisting of a coil, a braided mesh, a substrate, andcombinations thereof.
 13. The catheter assembly according to claim 11,wherein the reinforcement element is a stainless steel coil and thesleeve is composed of polyimide.
 14. The catheter assembly according toclaim 1, wherein the stylet further comprises a hydrophilic coating. 15.The catheter assembly according to claim 1, wherein the stylet furthercomprises a handle oriented in a direction corresponding to a directionof the bent configuration.